[vcf_etl%vcf_record] Create a `RecordCall` class

[dgomezpere]

• record.calls must be a list of RecordCall objects:

print(record.calls)
[out]:
    [
        <RecordCall class>,
        <RecordCall class>,
        <RecordCall class>,
        <RecordCall class>,
    ]

• A RecordCall object must have a sample and data (extends collections.OrderedDict class) properties.

print(record.calls[idx].sample)
[out]:
    "pepito"

print(record.calls[idx].data)
[out]:
    OrderedDict({
        "key1": value1,
        "key2": value2,
        "keyN": valueN,
    })

[segarmond]

Check setter for RecordCall

[dgomezpere]

Related commit: f2d4ce4